1. Field of the Invention
The present invention relates to a mobile communication terminal, an interference cancellation system, an interference cancellation method, and a base station.
2. Related Background Art
Conventionally, the TDD (Time Division Duplex) system is utilized as one of systems for substantializing two-way communications between mobile communication terminals like cellular phones and base stations. In the TDD system, uplink and downlink channels are switched over in the short period (e.g., 667 μs) whereby various signals are transmitted and received by making use of communication channels of the same frequency.
On the other hand, in the case where a mobile communication terminal is located in a reachable range of radio waves from a plurality of base stations, interference can occur between a signal from a base station in communication and signals from the other base stations. Interference occurs between a mobile communication terminal and a base station and also occurs between a plurality of mobile communication terminals. There is a proposal for Joint Detection as a technique of canceling such interference in the TDD system.
The Joint Detection is a process of calculating a demodulated signal D by a predetermined operational expression, based on received signal E received by the mobile communication terminal, spreading code C, and channel estimate H. The mobile communication terminal executes the Joint Detection upon reception of a signal to cancel the interference with the other mobile communication terminals or base stations present in the same cell. The Joint Detection is the technique that can also be applied to the CDMA (Code Division Multiple Access) system.